1. Field of the Invention
The invention relates to processing network messages between a network client and a network server. In particular, the invention relates to recovering from the loss of communication between a wireless client and server.
2. Description of the Related Art
Consumer desire for access to information, such as voice and data, is continually increasing. More recently, consumers are becoming mobile, moving about from one location to another and still wanting access to information. Devices that allow customers to access information while the customers are mobile are continuing to be developed. Mobile devices are placing increased demands on communication systems, in particular wireless communication systems.
Modern wireless communication systems are generally highly reliable and effective in transferring signals, such as voice or data, between multiple devices. A communications link is established between at least two devices and then the transfer of signals can occur. However, there are occasions when the established communication between devices can be prematurely interrupted, or “dropped”, resulting in the devices no longer being in communication with each other. Interruptions in communications are more prevalent in wireless communication systems than in a wired communication system, due in part to the physical connection between devices in the wired communication system being more stable, while there is no such physical connection in a wireless communication system.
In a wireless telecommunication system, for example, a cellular system, established communications might be dropped for a number of reasons. One reason for dropped communications is that a wireless device has left the coverage area of the local wireless system and is not picked up or transferred to a new system. For example, a cellular telephone system is typically divided into geographic cells, each of which is served by a base station which communicates with wireless devices located within the cell. All the cells together make up the coverage area of the cellular system. As the mobile device travels from cell to cell of the coverage area, the base stations transfer the device to a succeeding communications channel, maintaining the established communication.
If a mobile device travels outside the system coverage area, the wireless communication channel between the mobile device and the wireless system will be lost and the communication will be dropped. In some situations the mobile device can be entering the coverage area of a second cellular service provider. In this situation, the communication can continue with the mobile device in the other cellular system, if the second cellular service supports such communication.
Another reason that an established communication might be dropped in a cellular system is due to a failed handoff. For example, if a mobile telephone travels from a first cell to a second cell in the cellular system, the communication is handed off from a base station serving the first cell to a base station serving the second cell. In some situations the base station serving the second cell might not have any radio channels available for communication with the mobile device at the time of the handoff. In such a situation the established communication with the mobile device will be dropped. Another reason for dropped communications in a cellular system is referred to as coverage holes, which are areas in the geographic serving area which do not receive signals from the system. If a mobile device enters a coverage hole, communication with the serving base station will be lost and the communication will be dropped. Communication in a cellular system can also be dropped due to RF interference and equipment failures.
Dropped communication are very inconvenient to consumers. Re-establishment of the communication is left to the parties to the communication. This re-establishment can be somewhat difficult, especially where neither party knows the intention of the other party. For example, if the communication is a call between cell phones, both parties might attempt to call the other party, which can result in both parties receiving a “busy signal” and the connection being blocked. Alternatively, both parties might assume that the other party is going to initiate the call, resulting in no re-establishment of the call.
The dropped call situation is worsened in the case of a connection between a mobile device and a network, for example between a user's mobile Web browser and the Internet. If a mobile Web browser is in communication with a server on the Internet, and the communication is dropped, the mobile Web browser must re-establish communication with the server and then the user must re-navigate through the Web site until reaching the location in the Web site when the communication was dropped. In addition, information that the mobile Web browser transferred to the server can be lost due to the unexpected, premature, loss of communication. This type of interruption is especially inconvenient when a user is mid-way through an electronic transaction because lengthy information, such as, credit card data or delivery address must be re-entered.
Therefore, there is a need for an improved method and apparatus for recovering from a loss of communications in telecommunication networks.